I think it's amazing how, out of all the cars surrounding you on a busy street or highway the GPS can pick out your vehicle.
It is amazing to think about.
A brief history of GPS Accuracy (for those interested): I remember when GPS first became publicly available at a "reasonable price" (sometime in the early part of the 1990s) the accuracy was only guaranteed to within about 100 meters. (And that was only when the government was not using what was then called "Selective Availability", which was essentially a way to voluntarily degrade the accuracy of the system. The DOD's use of SA was gradually reduced during the 90's and was permanently abandoned at the turn of the century.) In actual practice, under ideal conditions, the early Magellan and Garmin receivers in that era could pinpoint you to within about 25-30 meters.
At first, there were not many satellites in operation. It was not until after 1995 when the full constellation of 27 first-generation GPS satellites was in orbit. That caused accuracy to greatly improve, but still nowhere near the degree of accuracy we see today. Over the years since then both transmitters and receivers have greatly improved, both in accuracy and in speed. We are currently in the third generation of the GPS system. Unaugmented accuracy is now guaranteed to within about 7 meters, with actual results in unobstructed locations more around 3 meters or better, most of the time. (Even your phone can tell you which area of your house you are sitting in, if you are near a window and picking up even a small array of satellites.)
After about 2006 many better GPS receivers also received WAAS signals (Wide Area Augmentation System). Developed by the FAA, mostly for aviation use, WAAS signals are generated from ground stations located in most widely populated areas of North America. With WAAS, the accuracy is about 5x better than without it. (Parts of Europe and Asia also have their own augmentation systems apart from WAAS).
However, today most commonly available GPS receivers (including Garmin and other units we use in our cars and on our Spyders) have become so sophisticated that they can obtain very near the accuracy of WAAS augumented GPS receivers from the satellite transmitters alone.
THAT is why today's GPS receivers can pinpoint almost the EXACT location of your vehicle on the highway in real time. And the average consumer price of these units keeps coming down year after year, while features and accuracy continue to go up.
Aviation grade GPS receivers today use both WAAS and Differential GPS which can pinpoint accuracy to within just a few centimeters near all but the smallest airports. The military today uses a completely different signal (transmitted from the same satellites) which is probably much more accurate than civilian GPS.
:clap:The gps helps track ones I've already seen. Is handy lil digital map that i do not have to fold, use a light, or marker:thumbup: Keeps up automatically. & as long as I keep updated & charged, it will stay handy. I particularly like when I do find and odd out of the way scenic location i want to share, it can give me an address or mark where I am so I can come back with friends:2thumbs: I have even have just let a friend use it to go see same location when they had time, & i didn't. Don't ever need to depend on one but they are handy. Personally having more than one helps too, so you can compare accuracy, i like the satellite hybrid view on phone:doorag: & smsmygps app I can just txt my friends where to meet via google maps:firstplace:
